BFD for MPLS LSPs Enhancement draft-chen-mpls-bfd-enhancement-01.txt

1. BFD for MPLS LSPs Enhancementdraft-chen-mpls-bfd-enhancement-01.txt Ning So (ning.so@verizonbusiness.com) Mach Chen (mach@huawei.com) Ville Hallivuori (ville.hallivuori@tellabs.com ) MPLS - 77th IETF Anaheim

2. BFD Enhancement Overview • Relax the rule of “One BFD session per FEC” to “One BFD session per LSP or pair of LSPs”. • Reduce the number of BFD sessions • Allows LSP ingress to signal the desired return path for any BFD session • Utilizes the Return-Path-Specified capability defined in RPS-LSP-PING (draft-chen-mpls-return-path-specified-lsp-ping) • Only one BFD session is provisioned onto a bidirectional Path • Controlled by a new TLV: Session Control TLV • The node with larger IP SHOULD initiate the signaling • Allows one BFD session to be used as protection trigger for a pair of unidirectional LSPs • The forwarding and returning path of the LSP pair are congruent MPLS - 77th IETF Anaheim

3. Diverse Transport Paths … 100 GE 100 GE ROUTER 1 NODE A NODE B … ROUTER 2 … … Uni - Directional LSP Bi - Directional LSP Multiple LSP … … Use Case for Enhanced BFD • Use case condition description • multiple uni-directional LSPs exist between Router 1 & 2, carrying different type of services • Multiple bi-directional LSPs exist between Node A&B, carried on diverse physical transport paths • Return-path-specified BFD enhancement can simplify the BFD session provisioning process • No need to log into both routers in order to deterministically select the physical paths on which the operators want to detect failure • In this case, the operator can provision 3 BFD sessions onto 6 uni-directional LSPs (3 in each direction) where those LSPs are carried on 3 diverse path. • The time savings can be very significant when activating a new router in a large network where full-mesh LSPs provisioning are required to support the services (e.g. VPLS) carried on the new router • Return-path-specified BFD enhancement can simplify the trouble shoot process • No need to log into both routers reduces customer down time and increase network availability • It is especially useful when the remote router is not accessible (belong to another carrier or all login sessions occupied), or the remote router is of different equipment vendor on which the trouble shooting operator is not trained MPLS - 77th IETF Anaheim

4. Differences between version 0 and version 1 • Following changes were made on Session establishment section based on the comments from Vishwas Manral: • Proposed to use Source Address TLV to carry the IP address of the initiator when IP forwarding is disabled (in MPLS-TP scenario) for IP address comparison • Clarified the process of BFD control packets when a single BFD session is provisioned to a bidirectional path • the initiator (ingress) MUST not send BFD packets before echo reply received • Ensure that the BFD session is complete for both directions before any BFD control packets are sent over the session • A new section (Section 5 Encapsulation) is added • Describes how to encapsulate the BFD control packets transmitted over the return LSP • Other minor editorial changes for error correction and clarification purposes MPLS - 77th IETF Anaheim

5. Acknowledgements Authors would like to thank Greg Mirsky, Vishwas Manral, Adrian Farrel, Peter Ashwood-smith and Xinchun Guo for their reviews and great input MPLS - 77th IETF Anaheim

6. Next Step • Should this draft progress within MPLS WG draft or should it be moved to BFD WG? MPLS - 77th IETF Anaheim